This study will measure the mechanical loading conditions that proceed pathological changes in soft tissues of diabetic amputees being fitted with their first below knee, permanent prosthesis. Our preliminary work has established a non-invasive method for monitoring skin response to prolonged loading, using tissue reflectance spectrometry (TRS). We have extensively characterized the post ischemia responses of spinal cord injured and multiple sclerosis subjects and will extend in this study the measurements to diabetic amputees. Our current work has also demonstrated an effective method for accommodating for the effects of skin pigmentation on the primary measurement parameters - superficial skin blood content and oxygenation. These parameters can now be accurately measured in black subjects and other ethnic groups. The first two years will concentrate on collecting normative TRS post ischemia response data on diabetic amputees at sites on the residual limb known to be at risk. The effect of repetitive vs prolonged loading, and amplitude of loading will also be contrasted. During this time TRS will also be used to dynamically characterize the blood content and oxygenation status of BK amputees who present at our clinic with localized pain and/or persistent skin redness. The investigators have also contributed to the development and evaluation of advanced pressure mapping technology for clinical seating and positioning applications. In the first two years we will further develop this technology for measurement of stump-socket interface pressures during everyday use of the prosthesis. In collaboration with Tekscan Inc., modifications to existing technology will be made in Years 1 and 3 to permit ambulatory monitoring of interface pressures. In years 3-5 we will study tissue response to loading history for over 100 BK diabetic amputees in the community, during the period immediately after the fitting of the patient's first permanent prosthesis. Four days after the fitting, the TRS will be used to evaluate areas of the residual limb that normally exhibit localized damage, inflammation or pain and the extent of any adverse responses will be measured. The detailed loading history that proceeded the tissue response will be extracted from the data collected during the monitoring period. Parameters to characterize loading history will include: number of loading repetitions; magnitude and duration of peak loads; duration of walking sessions; peak pressures during swing phase and pertinent clinical data.